This is an operation to reconstruct a torn anterior cruciate ligament. The anterior and posterior
cruciate ligaments are 2 of the main stabilisers of the knee. There are many other structures in the
knee that also contribute to stability, including the medial and lateral collateral ligaments and the
menisci. If any of these structures are damaged it will make the situation worse.
The anterior cruciate ligament is more commonly injured than the posterior. There can be a partial
tear of say 10% all the way up to a full tear. Some people tear the ACL and do not have much of a
problem. They can even continue to play sport. These people have knees where the other structures
are relatively tight so that the knee does not give way. Others are very dependent on the ACL and
their knees can give way walking down the street. Most people lie somewhere in between.
The decision to have a reconstruction is based on many factors.
1. Does your knee give way during normal walking or jogging?
2. Does it give way in a match situation and do you wish to continue to play at this level?
3. Does it give way at work and is your job relatively dangerous? For example do you work on
ladders or on scaffolding?
4. Are you having locking or pain in the knee on doing certain activities?
5. Are you willing to change your lifestyle to protect your knee?
If you answer YES to the first 4 items then you should consider an ACL reconstruction.
If you answer YES to item 5 you may not need it.
The operation will in 90% of cases give you a more stable knee.
Whether you have a reconstruction or not you are at an increased risk of getting osteoarthritis in the
knee. We do not know yet if the operation will make this less of a risk.
There is cartilage damage in 50% of patients with ACL tears. These patients do not do as well as
those that have no cartilage damage. Almost all patients with cartilage damage will have some
degree of arthritis after 15 years.
Surgery does not return the knee completely to the pre-injury state.
Women must be off the oral contraceptive pill for 4 weeks prior to surgery.
You will be in hospital for 1 night after the surgery. The operation lasts less than 2 hours.
There are 2 ways to reconstruct the anterior cruciate ligament.
1. Two of the hamstring tendons will be removed from the side of the knee. These tendons are
doubled over and then inserted through a hole in the Tibia (shin bone) and the Femur (thigh
bone). They are fixed in place with a combination of a plastic screw and a metal button. This
graft can be either 4 strands or 5 strands. A 5 strands graft is used when the 4 strands graft
needs to be a little bigger. I am tending to use bigger grafts so the 5 strands graft is probably
the commonest graft now.
2. In some cases the central part of the patellar tendon in the front of the knee with a block of
bone from the tibia and the patella is used. I use this if the patient has this done on the other
knee already and they are happy with the result. I also use it if I am doing a redo procedure
and the patient has already had a hamstring graft that has torn again. This is fixed in the tibia
and femur with screws.
There will be an ice pack on your knee after the operation. You can get up on crutches when you are
up to it. You will certainly be up on the day after the operation. You should use the crutches for 4
weeks to protect the leg. You will be able to take your weight on the leg. It is very important to
elevate the leg as often as possible for the first 2 weeks as this will reduce pain and swelling.
Physiotherapy will start on the day of the operation. It will be arranged for you in your area when
you go home. You will probably go at least once a week for the first 6 weeks.
There is a strict programme of rehabilitation set out which you will follow for 6 months. You can
access my programme at my website sportsinjurysurgery.ie.
You are advised to have a computer muscle strength test at 4 months and 6 months to assess your
progress before a full return to sport. This is called a Biodex test. You must commit to returning for
follow up visits to assess your knee before you step up your activity level.
There are risks attached to all operations.
There is a risk of cardiac or lung complications with a general anaesthetic. These are less than 1 in
1000. The risks are increased if you have a pre-existing medical condition. There is a risk of a deep
vein thrombosis in the leg veins. This is probably 1 in 40. The clot may travel to the lung. The risk of
this is about 1 in 100 cases. You will be given an injection to try to prevent a clot.
There is the possibility of infection in 1 in 250 cases. This can be very serious and may permanently
damage the graft and the knee.
There is a risk of a wound hematoma, which may cause the wound to break down and delay healing
for 6 weeks. Sometimes there is extensive swelling tracking down along the shin bone and this can
be quite painful and make it difficult to weight bear.
There is a high risk of skin nerve damage with any wound, which may lead to numb areas around the
wounds. At least 80% of ACL surgery patients will have a numb area down the front of their shin.
This may decrease in time but it could take one year and in a small number of cases it will be
Return to sport
Nobody knows for certain when it is safe to return to full sport. Some surgeons do not let their
patients play for 1 year. Others allow their patients go back after 6 months. Some of my patients
have gone back after 6 months but most wait 9 months. The graft will be stronger after 1 year and
will continue to strengthen up to 2 years after the operation.
You will not return to sport until your body has been fully rehabilitated. This is a combination of
muscle strength in the legs but also balance and co-ordination. Both these elements must be right
before you attempt to play. The computer muscle test is a good guide to your actual muscle strength.